Carrier relaxation due to both optical and nonradiative intraband transitions in silicon quantum dots (QDs) in SiO2 matrix is considered. Interaction of confined holes with optical phonons is studied. The Huang-Rhys factor governing intraband transitions induced by this interaction is calculated. The probability of intraband transition of a confined hole emitting several optical phonons is estimated. (C) 2008 Elsevier B.V. All rights reserved.